Dampening device for an offset printing press



April 21, 1970 s. SCHUHMANN 3,507,215

DAMPENING DEVICE FOR AN OFFSET PRINTING PRESS 5 Filed Aug. 31, 1967Inventor.- SlEG-Fm en San uH mam! BY Curl- United States Patent3,507,215 DAMPENIN G DEVICE FOR AN OFFSET PRINTING PRESS SiegfriedSchuhmann, Offenbach am Main, Germany, as-

signor to Roland Ofisetmaschinenfabrik Faber & Schleicher A.G.,Offenbach am Main, Germany, a German firm Filed Aug. 31, 1967, Ser. No.664,692 Claims priority, application Germany, Sept. 9, 1966,

Int. Cl. B41f 25/16, 31/12, 33/10 U.S. Cl. 101-148 6 Claims ABSTRACT OFTHE DISCLOSURE A dampening device for an offset printing press in whicha supervisory means is activated when the press has completed apredetermined number of operational cycles after feed of moisture to aroller for applying moisture to the plate cylinder of the press has beeninitiated. Activation of the supervisory means is utilized either toindicate that the roller is ready to be manually moved into engagementwith the plate cylinder of the press or to initiate automatically suchmovement. The dampening device further includes means which reduce for apredetermined number of cycles the moisture feed from the roller to theplate cylinder when the latter is in engagement with the roller but theblanket cylinder is not in engagement with the plate cylinder and theimpression cylinder. When during said predetermined number of cycles theblanket cylinder is moved into engagement with the plate cylinder andthe impression cylinder to start printing, the moisture feed by theroller to the plate cylinder is restored to normal but if the blanketcylinder is not moved into such position the moisture feed is stoppedcompletely.

The invention relates to dampening devices for offset printing machineswith a cylinder trip mechanism, and more particularly, to dampeningdevices including means for selectively discontinuing moisture feed torollers which are movable into and out of engagement with the platecylinder of the press for applying moisture thereto.

There are known dampening devices including a ductor roller dipping intoa liquid supply. The moisture is transmitted from the ductor roller tomoisture applying rollers by continuous or intermittent contact withintermediate rollers or by means of a lifting roller. The ductor rollerfeeds the moisture taken up by it to form rollers which, in turn,transfer the moisture to the plate cylinder of the press. Control of themoisture feed is effected by changing the rotational speed of the ductorroller, by changing the frequency of the oscillations of the liftingroller, by changing the mutual pressure between the coacting rollers orby additional squeezing rollers. Moisture applying form rollers as usedin dampening devices are generally coated with layers of natural fabric,paper or synthetic fabric, or have a rubber coating.

Depending upon the type of coating on the form rollers and the liquidwhich is used, the so-called moisture capacity of the form rollerschanges and thus also the length of time required for adjusting andstabilizing the moisture content of the form roller and thus of theplate cylinder.

As is evident, as soon as the press is stopped the coating on the formroller begins to dry. The extent of such drying depends, of course, uponthe length of the stoppage and the prevailing atmospheric conditions. Inany event, the printer must manually supply moisture to the form rollerprior to the starting of a printing operation or resumption of aprinting operation. It is customary that the printer supplies to fabriccovered form rollers an excess of moisture to prevent a smudging of therotating rollers with ink. When the form rollers are coated with rubber,the available moisture supplying time is so short that a single feed ofmoisture by the printer is generally not sufficient. Experience showsthat there is a danger of dryingout of the surface of rubber coated formrollers even during a short period of stoppage if the moisture feedcannot be maintained during such stoppage. Continuing 10 the supply ofthe moisture feed without change in quantity is not practical due to thelow moisture capacity of rubber coated form rollers and also due to thechange in the ratio between supply of moisture and consumption thereofwhen and while printing is stopped.

To leave dampening of the moisture applying rollers prior to thestarting of a printing operation or to the resumption of the printingoperation after a stoppage, to the judgment of the printer is risky.Obviously, misjudgment by the printer can result in wrong tones on theplate and also in emulsifying of the ink with the supplied moisture.Either effect is highly undesirable.

It is a broad object of the present invention to eliminate theaforepointed out disadvantages of dampening devices as heretofore knownand to provide a novel and improved dampening device which permits anaccurate control of the supply of moisture from the moisture applyingroller to the plate cylinder in accordance with the actually existingconditions.

A more specific object of the invention is to provide a novel andimproved dampening device of the general kind above referred to in whicha counting means indicates when the moisture applying roller is ready tobe moved into engagement with the plate cylinder.

Another more specific object of the invention is to provide a novel andimproved dampening device in which an adjustable counting means signalsthat the roller is ready for movement into engagement with the platecylinder when a predetermined number of operational cycles has beencompleted after starting the supply moisture to the roller. As a result,the moisture applying roller is moved into engagement with the platecylinder only when the roller is sufficiently moist. The extent ofmoisture taken up by the roller is variable by varying the number ofcycles but a degree of moisture content which has been found to befavorable can be reproduced at any time without difiiculty.

Another more specific object of the invention is to provide a novel andimproved dampening device of the general type above referred to in whichthe counting means automatically initiates movement of the moistureapplying roller into engagement with the plate cylinder when apredetermined number of cycles has been completed after starting of themoisture feed to the roller.

It is also an object of the invention to provide a novel and improveddampening device of the general kind above referred to in which a secondcounting means reduces the feed of moisture to the plate cylinder to alower value 'for a selected number of cycles when the printing operationhas been discontinued but the moisture applying roller remains inengagement with the cylinder. This has the advantage that during shortperiods of stoppage the dampening device remains operational and that atthe same time the reduced consumption of moisture due to thediscontinuance of the printing operation is compensated by acorrespondingly reduced moisture feed to the plate cylinder.

The reduction in the moisture feed can be effected by various meansdepending upon the type of dampening device used for instance, reducingthe r.p.m. of a ductor roller, by decreasing the oscillation frequencyof a swinging lifting roller or by changing the mutual pressure be:

3 tween coacting intermediate rollers. The maximum period of time duringwhich the reduced moisture feed is to be maintained can be readily andaccurately adjusted in accordance with the time of the expectedstoppage.

The invention also provides that the second counting means effects thedisengagement of the moisture applying roller and thus interruption ofthe moisture feed to the plate cylinder upon completion of the selectednumber of cycles. The dampening device is thus automatically renderedinoperative after a selected period of time when the printing operationis not resumed within such period. In other words, a continued andundesired operation of the dampening device is avoided.

The counting means according to the invention may be electrically ormechanically operated for instance, electric counters and time relaysmay be used or mechanical counters.

Other objects, features and advantages of the invention will be pointedout hereinafter and set forth in the appended claims constituting partof the application.

In the accompanying drawing a preferred embodiment of the invention isshown by way of illustration and not by way of limitation.

In the drawing:

FIG. 1 is a diagrammatic elevational view of an offset printing pressequipped with a dampening device according to the invention;

FIG. 2 is a diagrammatic elevational view of the dampening device, theform roller being shown in engagement with a plate cylinder of thepress;

FIG. 3 is a view similar to FIG. 2 but showing the roller withdrawn fromthe plate cylinder;

FIG. 4 is a block circuit diagram of the device. Referring now to thefigures more in detail, FIG. 1 shows a plate cylinder 2, a blanketcylinder 3 and an impression cylinder 4 rotatably mounted in aconventional manner in side walls 1 of the frame structure of the press.A conventional inker mechanism is diagrammatically indicated at 5 andthe dampening device at 6. The blanket cylinder 3 is journalled ineccentric bearings 7 so that it can be moved into and out of engagementwith plate cylinder 2 and impression cylinder 4 by being rotated in itsbearings. If current is supplied to a solenoid 8 bearings 7 are turnedin clockwise direction, thereby moving the blanket cylinder intothrown-in position, shown in full lines. Excitation of solenoid 9 turnsthe bearings 7 in counterclockwise direction thereby moving the blanketcylinder into the thrown-off position shown in dotted lines. T urning ofbearings 7 is limited by stops 10 and 11.

The shaft of impression cylinder 4 mounts a nose 12 which actuates aswitch 13 during each revolution of the cylinder.

As is shown in FIGS. 2 and 3, the dampening device 6 according to theinvention comprises a ductor roller or water fountain roller 15 dippinginto a receptacle 14 filled with water or another suitable liquid. Theductor roller is rotated by a speed variable electromotor 16 via agearing 17 and a chain 18. Ductor roller 15 engages with controllablepressure a water vibrator roller 19 which is rotated in a conventionalmanner by plate cylinder 2 via gears. The vibrator roller 19 is seatedon a shaft 45 on which are also seated two-arm levers 20 each of whichsupports on one arm a form roller 21 for applying moisture to the platecylinder. Roller 21 is journalled in eccentric bushings 22 the angularposition of which controls the pressure between roller 21 and watervibrator roller 19. A spring 23 stationarily mounted on one end andsecured with its other end to the second arm of levers 20 urges thelevers into engagement with a stop 24 in which position roller 21 iswithdrawn from plate cylinder 2 as is shown in FIG. 3.

To move roller 21 into engagement with cylinder 2 a solenoid 25 isenergized. A core 25a of this solenoid is linked to the second lever armso that upon energizetion of the solenoid levers 20' and with its roller21 are pivoted from the position of FIG. 3 into the position of FIG. 2.A set screw 26 also coacting with levers 20 serves to adjust the maximumpressure with which roller 21 can engage plate cylinder 2.

The operation of the dampening device according to the invention willnow be described in connection with the block diagram of FIG. 4.

To start the press, a drive motor 28 thereof is connected to a powerline 29 by operating a switch 27. To begin a printing operation, aswitch 30 is operated thereby connecting motor 16 to the power line. Themotor now turns at its fully working speed. Operation of switch 30 alsoconnects switch 13 into the circuit. As stated before, this switch isonce operated by nose 12 during each rotation of impression cylinder 4and each operation of the switch feeds a pulse to an adjustable counter31. This counter is set for a predetermined number of rotational cyclesof the cylinder and when this number is reached a suitable audible orvisual supervising means such as a signal lamp 32 is connected. As hasbeen explained before, activation of the supervising means indicatesthat the fabric or other layer on roller 21 has absorbed sufficientmoisture and that the roller is now ready to be moved into engagementwith plate cylinder 2. The roller is moved into such engagement bymanual operation of a switch 33 which when operated connects solenoid 25with the power line.

The dampening device now functions in a conventional manner.

Instead of effecting movement of roller 21 into engagement with platecylinder 2 by manual operation, the dampening device can also bearranged for automatic operation. To this end the signal lamp 32 isconnected by a wire 32a to switch 33 so that simultaneously withconnecting lamp 32 to the power line by counter 31 switch 33 isautomatically operated. Accordingly, lamp 32 in conjunction with switch33 constitutes an automatically operated supervising means. Illuminationof lamp 32 then indicates that roller 21 is in engagement with platecy1in der 2 and has started feeding moisture to the same.

The press is now ready for printing.

After the paper feed to the press has been started, solenoid 8 isenergized by operating a starter switch 34 for the press. As previouslystated, solenoid 8 is part of a cylinder trip mechanism for movingblanket cylinder 3 into engagement with plate cylinder 2 and impressioncylinder 4, solenoid 9 being the solenoid of the mechanism fordisengaging cylinder 3 from cylinders 2 and 4.

Operation of switch 34 also causes via a wire 35 resetting of counter 31to its zero position. The counter is thus ready for the next cycle andlamp 32 blinks out. When new a switch 36 is operated either manually orby a conventional detecting device and causes energization of solenoid 9and thus withdrawal of the blanket cylinder from the two othercylinders, a second adjustable counter 37 is readied for pulses fed toit by switch 13. Moreover, a speed regulator 39 for motor 16 is set viaa wire 38 so that motor 16 now rotates with a rotational speed less thanits normal working speed. As a result, roller 21 which remains inengagement with plate cylinder 2 will supply to this cylinder lessmoisture than if motor 16 runs at full speed but with still sufiicientmoisture so that the press is immediately ready for resumption of theprinting operation, if desired.

Counter 37 is set for a pre-selected number of cycles and if printing isresumed by operation of starter switch 34 before the number of cyclesset in counter 37 has been reached, the counter is reset to zero via awire 40. Moreover, the r.p.m. of motor 16 is brought back to the fullworking speed via wire 38 and speed regulator 39. However, if printingis not resumed before the number of cycles for which counter 37 is setis reached, solenoid 25 is disconnected via a switch 41 and as a result,roller 21 becomes disengaged from plate cylinder 2. Furthermore, thespeed regulator is reset for the full rotational speed of motor 16 viawire 38 and the motor 16 itself is disconnected by switch 30.

The next cycle is initiated as hereinbefore described by again operatingstarter switch 30. By opening switch 27 motor 28 is stopped and all thecircuit components return into the starting position thereof.

Switches 27, 30, 33, 34 and 36 are preferably in the form of heavycurrent relays which hold contacts for locking-in the circuit componentsin a conventional manner. Circuit connections suitable for the purposeare well known and are not shown to simplify the circuit diagram.

What is claimed is:

1. A dampening device for an olfset printing press including a blanketcylinder movable into and out of a throw-in position with a platecylinder and an impression cylinder, and a moisture-applying rollermovable into and out of moisture-transmitting engagement with said platecylinder, said dampening device comprising in combination:

moving means for moving said moisture applying roller into and out ofmoisture transmitting engagement with the plate cylinder;

means for supplying moisture to said roller;

powder driven actuating means operable for activating said moisturesupplying means to supplying moisture to said roller at a predeterminedrate;

blanket cylinder moving means for moving the blanket cylinder into andout of the throw-in position;

a supervising means arranged to be operated upon moistening of theroller to a degree selected as being sufficient for movement of theroller into moisture-transmitting engagement with the plate cylinder;

first adjustable counting means counting operational cycles of theprinting press and connected in an energizing circuit with saidsupervising means to operate the same upon completion of a predeterminednumber of cycles, said first counting means being connected in anenergizing circuit with said power driven actuating means to beactivated by the same for said predetermined number of cycles when theactuating means are operated for activating the moisture supplyingmeans, said number of cycles being such that the selected degree ofmoisture is supplied to the roller by the moisture supplying means; and

second adjustable counting means coacting with said power drivenactuating means to operate the same for reducing the rate of moisturesupplied to the roller by said moisture supplying means below saidpredetermined rate for a second predetermined number of cycles ascounted by the second counting means, said second coutning means beingactivated when said blanket cylinder moving means is operated to movethe blanket cylinder out of the thrownin position, operation of theblanket cylinder moving means for movement of the blanket cylinder intothe throw-in position during said predetermined number of cycles ascounted by the second counting means operating said actuating means forrestarting the predetermined rate of moisture supplied to said roller bysaid moisture supplying means.

2. The dampening device according to claim 1 wherein said power drivenactuating means comprise movable ductor means for feeding moisture froma supply of moisture to said roller and drive means for driving saidductor means for the purpose aforesaid, said second counting meansreducing the speed of said drive means when activated by movement of theblanket cylinder out of the thrown-in position with the plate cylinderand the impression cylinder.

3. The dampening device according to claim 1 and comprising meanscontrolled 'by said second counting means for actuating said rollermoving means to move the roller out of engagement with the platecylinder and deactivating said power driven actuating means when theblanket cylinder is not moved into engagement with the plate cylinderand the impression cylinder during said second predetermined number ofcycles counted by the second counting means.

4. The dampening device according to claim 1 wherein said supervisingmeans comprises an indicating means, completion of the counting of saidfirst predetermined number of cycles by the first counting meansenergizing said indicating means thereby indicating that the selecteddegree of moisture is present on said roller.

5. The dampening device according to claim 1 wherein said supervisingmeans comprises a switch means for controlling said roller moving means,said switch means being connected in circuit with said first countingmeans, said first counting means upon counting the first predeterminednumber of cycles operating said switch means for moving the roller intomoisture transmitting engagement with the plate cylinder.

6. The dampening device according to claim 1 wherein said supervisingmeans comprises an indicating means and a switch means for controllingsaid roller moving means, both said means being connected in circuitwith said first counting means, said first count ng means upon countingthe first predetermined number of cycles energizing said circuitconnected to the indicating means and the switch means to operate theindicating means to indicate the presence of the selected degree ofmoisture present on said roller and the switch means to actuate theroller moving means for moving said roller into moisture transmittingengagement with the plate cylinder.

References Cited UNITED STATES PATENTS 1,254,338 1/1918 Mascord 101-3511,612,061 12/1926 Sanker 101-148 2,971,461 2/1961 Bradford et al.101-350 XR 3,191,528 6/1965 Jorgensen 101-148 3,274,932 9/1966 Caza101-351 ROBERT E. PULFREY, Primary Examiner C. D. CROWDER, AssistantExaminer U.S. Cl. X.R. 101-351

